1. Field of the Invention
This invention relates to chair structures, and more particularly, to an improved chair structure that is well-suited for outdoor use and provides swiveling and rocking motions.
2. Description of the Related Art
Outdoor furniture can be found in a wide variety of locations, such as, for example, outdoor restaurants, patios, and backyards. Outdoor furniture takes a wide variety of different forms but is typically manufactured from plastic and/or metal components to withstand the damaging effects of exposure to sun and moisture.
A common piece of outdoor furniture is the outdoor chair. Most outdoor chairs are constructed as rigid, unitary structures. However, for comfort and convenience, some outdoor chairs have a seat portion that is adapted to swivel relative to a base portion while other chairs provide the user with the ability to rock forward and backward. Still other chairs provide both swiveling and rocking motions.
In order to provide a rocking motion, some chairs include a pair of curved rails mounted beneath a seat portion of the chair. The curved rails contact the ground and are shaped to allow the user to rock back and forth with a smooth and comfortable motion. However, rocking chairs having curved rails are typically quite large and cumbersome and do not cooperate well with a table. Furthermore, curved rails are adapted for use on a relatively flat and smooth surface. The ground in an outdoor environment is often rough and uneven and therefore curved rail rocking chairs are not well-suited for outdoor use. In addition, curved rail rocking chairs are usually constructed of wood, are quite heavy and can be difficult to transport.
Rocking chairs constructed with a base portion that is fixed relative to the ground are better suited for use in an outdoor environment. To provide a rocking motion, a fixed-base chair structure includes a flexible coupling member that is located between the base portion and the seat portion. Fixed-base rocking chairs are typically less bulky than curved rail rocking chairs. As a result, fixed-base rocking chairs are more compact and may be used with a table in a more practical fashion. In addition, they do not require a smooth, flat surface.
A flexible coupling member used with a fixed-based rocking chair may take a variety of different forms. However, in each case, the flexible coupling member allows movement of the seat portion relative to the base portion. Flexible coupling members of this type are typically constructed of a steel alloy. Over the years, steel has been a preferred material for flexible coupling members because steel provides a desirably smooth and soft rocking motion while, at the same time, providing sufficient strength to accommodate a wide variety of body weights. In addition, a flexible steel structure can be subjected to a very large number of working cycles with minimal changes in stiffness or brittleness.
Although steel has many desirable qualities for use as a flexible coupling member, steel has numerous shortcomings that limit its desirability and usefulness for certain applications. For example, steel is susceptible to rust and corrosion when exposed to moisture. Rust and corrosion can substantially decrease the aesthetic appeal of the chair and can also diminish the structural integrity of the chair. In another shortcoming, steel has a relatively high density and is therefore heavy and cumbersome as compared with many other materials. As a result, a chair having steel components can be quite difficult to move. In yet another shortcoming, steel has a relatively high heat capacity and can therefore become uncomfortably hot when exposed to direct sunlight.
Due to these and other shortcomings associated with the use of steel, aluminum has become an increasingly popular material for use in outdoor furniture components. Aluminum is lightweight, rust-resistant, and is better suited for use in direct sunlight. However, in the past, attempts to manufacture flexible components from aluminum have not been successful because aluminum does not have the same desirable flexibility and strength of steel. In particular, a flexible coupling member made of aluminum has not been capable of providing the desirable qualities of a steel spring while providing sufficient structural integrity to ensure safe use. Accordingly, attempts to manufacture rocking chairs using flexible coupling members made from aluminum or aluminum alloys have not been met with widespread success.
Thus, there exists a need for a fixed-base chair structure formed, at least in part, from lightweight, rust resistant, aluminum components that is capable of providing a desirably smooth and soft rocking movement. It is desirable that such a chair structure be capable of providing a swivel motion. It is also desirable that such a chair structure include a flexible coupling member that is capable of providing the strength and durability to be used with a wide variety of body weights over a very large number of rocking cycles. Furthermore, such a chair should be configured to minimize undesirable lateral rocking motions. To be practical, such a chair must be easy to transport and inexpensive to manufacture. The present invention addresses these needs.
The present invention provides a new and improved, rugged, lightweight, outdoor rocking chair that provides a desirably comfortable rocking motion using an improved spring mechanism that is preferably formed from aluminum alloy. The spring mechanism includes at least one C-shaped member (i.e., xe2x80x9cC-springxe2x80x9d) that provides a flexible coupling member between a fixed base portion and a seat portion. The C-spring is manufactured with a contoured profile that provides desirable strength and flexibility.
In one aspect of the invention, the chair includes at least one C-spring that is strong, lightweight and has a relatively thin profile. The C-spring is preferably formed from an aluminum alloy and therefore will not rust when exposed to sunlight and moisture. In a significant feature of the invention, the C-spring is formed with a contoured profile of variable thickness. The C-spring is preferably contoured to provide a cross-sectional profile having a thin middle portion and thicker side portions. As a result of the contoured profile, the C-spring has excellent structural integrity while providing high torsional stiffness to reduce undesirable lateral movements of the seat portion relative to the base portion. Such a contoured C-spring also provides a lightweight, rugged construction that is capable of withstanding a wide variety of body weights over a large number of working cycles.
In a preferred embodiment, the chair has two aluminum C-springs that are mounted in a spaced-apart configuration. The C-springs are constructed to provide a spring constant that allows the seat portion to be rocked in a forward and backward motion over a desirable range of motion. At the same time, the spacing of the C-springs creates a very stable structure that resists undesirable lateral rocking movement.
In another aspect of the invention, the rocking chair of the present invention is characterized by a seat portion, a fixed base and a pair of spaced-apart aluminum C-springs which flexibly couple the seat portion to the base portion. The C-springs are mounted at opposite ends of a horizontal support. To provide a swivel motion, a vertical post extends downward from the horizontal support. The bottom end portion of the post is received by a center hole in a fixed base. The post is capable of rotating within the hole to provide the swivel motion. The fixed base is configured for contacting the ground to provide a stable support. The fixed base may take a variety of different forms, including, but not limited to, three legs, four legs, or a circular member.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention.